package com.cc.dao;

import javax.xml.parsers.FactoryConfigurationError;
import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

//操作数据库的公共类
public class BaseDao {
    private static String driver;
    private static String url;
    private static String username;
    private static String password;

    static {
        Properties properties = new Properties();
        InputStream is = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");//通过类加载器读取资源
        try {
            properties.load(is);
        } catch (IOException e) {
            e.printStackTrace();
        }
        driver = properties.getProperty("driver");
        url = properties.getProperty("url");
        username = properties.getProperty("username");
        password = properties.getProperty("password");
    }

    //获取数据库连接
    public static Connection getConnection(){
        Connection connection = null;
        try {
            Class.forName(driver);
            connection = DriverManager.getConnection(url, username, password);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return connection;
    }

    //编写查询公共类
    public static ResultSet execute(Connection connection,PreparedStatement preparedStatement,ResultSet resultSet,String sql,Object[] params) throws SQLException {
        preparedStatement = connection.prepareStatement(sql);
        for (int i = 0; i < params.length; i++) {
            //setObject,占位符从1开始，但数组从0开始
            preparedStatement.setObject(i+1,params[i]);
        }
        resultSet = preparedStatement.executeQuery();
        return resultSet;
    }

    //编写增删改查公共方法
    public static int execute(Connection connection,PreparedStatement preparedStatement,String sql,Object[] params) throws SQLException {
        preparedStatement = connection.prepareStatement(sql);
        for (int i = 0; i < params.length; i++) {
            //setObject,占位符从1开始，但数组从0开始
            preparedStatement.setObject(i+1,params[i]);
        }
        int updatePows = preparedStatement.executeUpdate();
        return updatePows;
    }

    //释放资源
    public static boolean closeResource(Connection connection,PreparedStatement preparedStatement,ResultSet resultSet){
        boolean flag = true;
        if(resultSet!=null){
            try {
                resultSet.close();
                //GC回收
                resultSet = null;
            } catch (SQLException e) {
                e.printStackTrace();
                flag = false;
            }
        }

        if(preparedStatement!=null){
            try {
                preparedStatement.close();
                //GC回收
                preparedStatement = null;
            } catch (SQLException e) {
                e.printStackTrace();
                flag = false;
            }
        }

        if(connection!=null){
            try {
                connection.close();
                //GC回收
                connection = null;
            } catch (SQLException e) {
                e.printStackTrace();
                flag = false;
            }
        }

        if(resultSet!=null){
            try {
                resultSet.close();
                //GC回收
                resultSet = null;
            } catch (SQLException e) {
                e.printStackTrace();
                flag = false;
            }
        }

        return flag;

    }
}
